This invention is in the area of biologically active nucleosides, and specifically includes antiviral compositions that include a [5-carboxamido or 5-fluoro]-2xe2x80x2, 3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-pyrimidine nucleoside or [5-carboxamido or 5-fluoro]-3xe2x80x2-modified-pyrimidine nucleoside, or its physiologically acceptable derivative, or physiologically acceptable salt.
In 1981, acquired immune deficiency syndrome (AIDS) was identified as a disease that severely compromises the human immune system, and that almost without exception leads to death. In 1983, the etiological cause of AIDS was determined to be the human immunodeficiency virus (HIV). The World Health Organization estimates that currently 13 million people worldwide are infected with HIV and that forty million people will be infected by the year 2000. Each day approximately 5,000 people are newly infected.
In 1985, it was reported that the synthetic nucleoside 3xe2x80x2-azido-3xe2x80x2-deoxythymidine (AZT) inhibits the replication of a human immunodeficiency virus. Since then, a number of other synthetic nucleosides, including 2xe2x80x2,3xe2x80x2dideoxyinosine (DDI), 2xe2x80x2,3xe2x80x2-dideoxycytidine (DDC), and 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydrothymidine (D4T), have been proven to be effective against HIV. After cellular phosphorylation to the 5xe2x80x2-triphosphate by cellular kinases, these synthetic nucleosides are incorporated into a growing strand of viral DNA, causing chain termination due to the absence of the 3xe2x80x2-hydroxyl group. They can also inhibit the viral enxyme reverse transcriptase.
The success of various synthetic nucleosides in inhibiting the replication of HIV in vivo or in vitro has led a number of researchers to design and test nucleosides that substitute a heteroatom for the carbon atom at the 3xe2x80x2-position of the nucleoside. Norbeck, et al., disclosed that (xc2x1)-1-[(2xcex2,4xcex2)-2-(hydroxymethyl)-4-dioxolanyl]thymine (referred to as (xc2x1)-dioxolane-T) exhibits a modest activity against HIV (EC50 of 20 xcexcM in ATH8 cells), and is not toxic to uninfected control cells at a concentration of 200 xcexcM. Tetrahedron Letters 30 (46), 6246, (1989). European Patent Application Publication No. 0 337 713 and U.S. Pat. No. 5,041,449, assigned to IAF BioChem International, Inc., disclose that racemic 2-substituted-4-substituted-1,3-dioxolanes exhibit antiviral activity.
U.S. Pat. No. 5,047,407 and European Patent Application Publication No. O 382 526, also assigned to IAF Biochem International, Inc. disclose a number of racemic 2-substituted-5-substituted-1,3-oxathiolane nucleosides with antiviral activity, and specifically report that the racemic mixture (about the C4xe2x80x2-position) of the C1xe2x80x2-xcex2 isomer of 2-hydroxymethyl-5-(cytosin-1-yl)-1,3-oxathiolane (referred to below as (xc2x1)-BCH-189) has approximately the same activity against HIV as AZT, and no cellular toxicity at the tested levels. (xc2x1)-BCH-189 has also been found to inhibit the replication of AZT-resistant HIV isolates in vitro from patients who have been treated with AZT for longer than 36 weeks. The (xe2x88x92)-enantiomer of the xcex2-isomer of BCH-189, known as 3TC, which is highly potent against HIV and exhibits little toxicity, is in the final stages of clinical review for the treatment of HIV.
It has also been disclosed that (xe2x88x92)-cis-2-hydroxymethyl-5-(5-fluorocytosin-1-yl)-1,3-oxathiolane (xe2x80x9cFTCxe2x80x9d) has potent HIV activity. Schinazi, et al., xe2x80x9cSelective Inhibition of Human Imnunodeficiency Viruses by Racemates and Enantiomers of cis-5-Fluoro-1-[2-(Hydroxymethyl)-1,3-Oxathiolane-5-yl]Cytosinexe2x80x9d Antimicrobial Agents and Chemotherapy, November 1992, page 2423-2431.
Another virus that causes a serious human health problem is the hepatitis B virus (referred to below as xe2x80x9cHBVxe2x80x9d). HBV is second only to tobacco as a cause of human cancer. The mechanism by which HBV induces cancer is unknown, although it is postulated that it may directly trigger tumor development, or indirectly trigger tumor development through chronic inflammation, cirrhosis, and cell regeneration associated with the infection.
After a two to six month incubation period in which the host is unaware of the infection, HBV infection can lead to acute hepatitis and liver damage, that causes abdominal pain, jaundice, and elevated blood levels of certain enzymes. HBV can cause fulminant hepatitis, a rapidly progressive, often fatal form of the disease in which massive sections of the liver are destroyed.
Patients typically recover from acute hepatitis. In some patients, however, high levels of viral antigen persist in the blood for an extended, or indefinite, period, causing a chronic infection. Chronic infections can lead to chronic persistent hepatitis. Patients infected with chronic persistent HBV are most common in developing countries. By mid-1991, there were approximately 225 million chronic carriers of HBV in Asia alone, and worldwide, almost 300 million carriers. Chronic persistent hepatitis can cause fatigue, cirrhosis of the liver, and hepatocellular carcinoma, a primary liver cancer.
In western industrialized countries, high risk groups for HBV infection include those in contact with HBV carriers or their blood samples. The epidemiology of HBV is very similar to that of acquired immune deficiency syndrome, which accounts for why HBV infection is common among patients with AIDS or AIDS-related complex. However, HBV is more contagious than HIV.
Both FTC and 3TC exhibit activity against HBV. Furman, et al., xe2x80x9cThe Anti-Hepatitis B Virus Activities, Cytotoxicities, and Anabolic Profiles of the (xe2x88x92) and (+) Enantiomers of cis-5-Fluoro-1-[2-(Hydroxymethyl)-1,3-oxathiolane-5-yl]Cytosinexe2x80x9d Antimicrobial Agents and Chemotherapy, December 1992, page 2686-2692.
A human serum-derived vaccine has been developed to immunize patients against HBV. While it has been found effective, production of the vaccine is troublesome because the supply of human serum from chronic carriers is limited, and the purification procedure is long and expensive. Further, each batch of vaccine prepared from different serum must be tested in chimpanzees to ensure safety. Vaccines have also been produced through genetic engineering. Daily treatments with xcex1-interferon, a genetically engineered protein, has also shown promise.
In light of the fact that acquired immune deficiency syndrome, AIDS-related complex, and hepatitis B virus have reached epidemic levels worldwide, and have tragic effects on the infected patient, there remains a strong need to provide new effective pharmaceutical agents to treat these diseases and that have low toxicity to the host.
Therefore, it is an object of the present invention to provide a method and composition for the treatment of human patients infected with HIV.
It is another object of the present invention to provide a method and composition for the treatment of human patients or other host animals infected with HBV.
A method and composition for the treatment of HIV and HBV infections in humans and other host animals is disclosed that includes the administration of an effective amount of a [5-carboxamido or 5-fluoro]-2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2, 3xe2x80x2-didehydro-pyrimidine nucleoside or a [5-carboxamido or 5-fluoro]-3xe2x80x2-modified-pyrimidine nucleoside, or a mixture or a pharmaceutically acceptable derivative thereof, including a 5xe2x80x2 or N4 alkylated or acylated derivative, or a pharmaceutically acceptable salt thereof, in a pharmaceutically acceptable carrier.
Specifically, compounds of the structure: 
wherein:
X is O, S, CH2, CHF, or CF2;
Y is O, S, CH2, CHF, CF2;
Z is independently O, S or Se;
R1 is independently H or F;
R2 is independently H, OH, C1 to C6 alkyl, or C(O)(C1 to C6 alkyl);
R3 is H, C(O)(C1-C6 alkyl); alkyl, or mono-, di- or triphosphate; and
R4 is independently H, F, Cl, Br, I, OH,
xe2x80x94O(C1-C6alkyl), xe2x80x94SH, xe2x80x94S(C1-C6alkyl); or
xe2x80x94C1-C6alkyl.
In a preferred embodiment for 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-nucleosides, Y is O or S; Z is O; R1 is H; R is H; and R3 is H. In a preferred embodiment for the 3xe2x80x2-modified lipyrimidine nucleosides, X is O or S; Y is O; Z is O; R1 is H; R2 is H; R3 is H, and R4 is independently H or F. The term xe2x80x9cindependentlyxe2x80x9d means that the groups can vary within the compound.
Preferred compounds include the racemic mixture, xcex2-D and xcex2-L isomers of the following compounds: 2-hydroxymethyl-5(5xe2x80x2-carboxamidouracil-1xe2x80x2-yl)-1,3-oxathiolane; 2-hydroxymethyl-4-(N-5xe2x80x2-carboxamidouracil-1xe2x80x2-yl)-1,3-dioxolane; 2-hydroxymethyl-4-(N-5xe2x80x2-flubrocytosin-1xe2x80x2-yl)-1,3-dithiolane; 2-hydroxymethyl-4-(N-5xe2x80x2-carboxamidouracil-1xe2x80x2-yl)-1,3-dithiolane; 2-hydroxymethyl-4-(N-5xe2x80x2-fluorocytosin-1xe2x80x2-yl)-1,3-oxathiolane; 2-hydroxymethyl-4-(N-5xe2x80x2-carboxamidouracil-1xe2x80x2-yl)-1,3-oxathiolane; 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-5-fluorocytidine; 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-5-carboxamidocytidine; 2xe2x80x2,3xe2x80x2-dideoxy-5-fluorocytidine; 2xe2x80x2,3xe2x80x2-dideoxy-5-carboxamidocytidine; 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-2xe2x80x2, 5-difluorocytidine; 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-2xe2x80x2-fluoro-5-carboxamidocytidine, 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-3xe2x80x2, 5-difluorocytidine; 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-3xe2x80x2-fluoro-5-carboxamidocytidine; 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-2xe2x80x2,3xe2x80x2, 5-trifluorocytidine; 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-2xe2x80x2, 3xe2x80x2-difluoro-5-carboxamidocytidine; 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-5-fluorocytidine; 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-5-carboxamidocytidine; 2xe2x80x2,3xe2x80x2-dideoxy-5-fluorocytidine; 2xe2x80x2,3xe2x80x2-dideoxy-5-carboxamidocytidine; 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-2xe2x80x2,5-difluorocytidine; 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-2xe2x80x2-fluoro-5-carboxamidocytidine; 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-3xe2x80x2,5-difluorouridine; 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-3xe2x80x2-fluoro-5-carboxamidouridine; 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-2xe2x80x2,3xe2x80x2,5-trifluorouridine; and 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-2xe2x80x2,3xe2x80x2-difluoro-5-carboxamidouridine.
In another embodiment, the active compound or its derivative or salt can be administered in combination or it alternation with another antiviral agent, such as an anti-HIV agent or anti-HBV agent, including those described above. In general, during alternation therapy, an effective dosage of each agent is administered serially, whereas in combination therapy, an effective dosage of two or more agents are administered together. The dosages will depend on absorption, inactivation, and excretion rates of the drug as well as other factors known to those of skill in the art. It is to be noted that dosage values will also vary with the severity of the condition to be alleviated. It is to be further understood that for any particular subject, specific dosage regimens and schedules should be adjusted over time according to the individual need and the professional judgment of the person administering or supervising the administration of the compositions.
Nonlimiting examples of antiviral agents that can be used in combination with the compounds disclosed herein include the (xe2x88x92)-enantiomer of 2-hydroxymethyl-5-(5-fluorocytosin-1-yl)-1,3-oxathiolane (FTC); the (xe2x88x92)-enantiomer of 2-hydroxymethyl-5-(cytosin-1-yl)-1,3-oxathiolane (3TC); carbovir, acyclovir, interferon, famciclovir, penciclovir, AZT, DDI, DDC, L-(xe2x88x92)-FMAU, and D4T.
The compounds can also be used to treat equine infectious anemia virus (EIAV), feline immunodeficiency virus, and simian imunodeficiency virus. (Wang, S., Montelaro, R., Schinazi, R. F., Jagerski, B., and Mellors, J. W.: Activity of nucleoside and non-nucleoside reverse transcriptse inhibitors (NNRTI) against equine infectious anemia virus (EIAV). First National Conference on Human Retroviruses and Related Infections, Washington, D.C., Dec. 12-16, 1993; Sellon D. C., Equine Infectious Anemia, Vet. Clin. North Am. Equine Pract. United States, 9: 321-336, 1993; Philpott, M. S., Ebner, J. P., Hoover, E. A., Evaluation of 9-(2-phosphonylmethoxyethyl) adenine therapy for feline immunodeficiency virus using a quantative polymerase chain reaction, Vet. Immunol. Immunopathol. 35:155-166, 1992.)
As used herein, the term xe2x80x9cenantiomericaily enriched nucleosidexe2x80x9d refers to a nucleoside composition that includes at least 95% to 98%, or more preferably, 99% to 100%, of a single enantiomer of that nucleoside.
The term C1-C6 alkyl includes methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, cyclopehtyl, isopentyl, neopentyl, hexyl, isohexyl, cyclohexyl, cyclohexylmethyl, 3-methylpentyl, 2,2-dimethylbutyl, and 2,3-dimethylbutyl.
The invention as disclosed herein is a method and composition for the treatment of HIV and HBV infections, and other viruses replicating in like manner, in humans or other host animals, that includes administering an effective amount of a [5-carboxamido or 5-fluoro]-2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-pyrimidine nucleoside or [5-carboxamido or 5-fluoro]-3xe2x80x2-modified-pyrimidine nucleoside, a pharmaceutically acceptable derivative, including a 5xe2x80x2 or, N4 alkylated or acylated derivative, or a pharmaceutically acceptable salt thereof, in a pharmaceutically acceptable carrier. The compounds of this invention either possess antiretroviral activity, such as anti-HIV-1, anti-HIV-2, anti-HBV, and anti-simian immunodeficiency virus (anti-SIV) activity themselves or are metabolized to a compound that exhibits antiretroviral activity.
The disclosed compounds or their pharmaceutically acceptable derivatives or salts or pharmaceutically acceptable formulations containing these compounds are useful in the prevention and treatment of HIV infections and other related conditions such as AIDS-related complex (ARC), persistent generalized lymphadenopathy (PGL), AIDS-related neurological conditions, anti-HIV antibody positive and HIV-positive conditions, Kaposi""s sarcoma, thrombocytopenia purpurea and opportunistic infections. In addition, these compounds or formulations can be used prophylactically to prevent or retard the progression of clinical illness in individuals who are anti-HIV antibody or HIV-antigen positive or who have been exposed to HIV.
The compound and its pharmaceutically acceptable derivatives or pharmaceutically acceptable formulations containing the compound or its derivatives are also useful in the prevention and treatment of HBV infections and other related conditions such as anti-HBV antibody positive and HBV-positive conditions, chronic liver inflammation caused by HBV, cirrhosis, acute hepatitis, fulminant hepatitis, chronic persistant hepatitis, and fatigue. These compounds or formulations can also be used prophylactically to prevent or retard the progression of clinical illness in individuals who are anti-HBV antibody or HBV-antigen positive or who have been exposed to HBV.
The compound can be converted into a pharmaceutically acceptable ester by reaction with an appropriate esterifying agent, for example, an acid halide or anhydride. The compound or its pharmaceutically acceptable derivative can be converted into a pharmaceutically acceptable salt thereof in a conventional manner, for example, by treatment with an appropriate base. The ester or salt of the compound can be converted into the parent compound, for example, by hydrolysis.
In summary, the present invention includes the following features:
(a) [5-carboxamido or 5-fluoro]-2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-pyrimidine nucleosides and [5-carboxamido or 5-fluoro]-3xe2x80x2 -modified-pyrimidine nucleosides, as outlined above, and pharmaceutically acceptable derivatives and salts thereof;
(b) [5-carboxamido or 5-fluoro]-2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-pyrimidine nucleosides and [5-carboxamido or 5-fluoro]-3xe2x80x2-modified-pyrimidine nucleosides, and pharmaceutically acceptable derivatives and salts thereof for use in medical therapy, for example for the treatment or prophylaxis of a HIV or HBV infection;
(c) use of [5-carboxamido or 5-fluoro]-2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-pyrimidine nucleosides and [5-carboxamido or 5-fluoro]-3xe2x80x2-modified-pyrimidine nucleosides, and pharmaceutically acceptable derivatives and salts thereof in the manufacture of a medicament for treatment of a HIV or HBV infection;
(d) pharmaceutical formulations comprising [5-carboxamido or 5-fluoro]-2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-pyrimidine nucleosides and [5-carboxamido or 5-fluoro]-3xe2x80x2-modified-pyrimidine nucleosides or a pharmaceutically acceptable derivative or salt thereof together with a pharmaceutically acceptable carrier or diluent; and
(e) processes for the preparation of [5-carboxamido or 5-fluoro]-2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-pyrimidine nucleosides and [5-carboxamido or 5-fluoro]-3xe2x80x2-modified-pyrimidine nucleosides, as described in more detail below.
I. Active Compound, and Physiologically Acceptable Derivatives and Salts Thereof
The antivirally active compounds disclosed herein are [5-carboxamido or 5-fluoro]-2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-didehydro-pyrimidine nucleosides and [5-carboxamido or 5-fluoro]-3xe2x80x2-modified-pyrimidine nucleosides, in the racemic or xcex2-D or xcex2-L enantiomerically enriched form.
The active compound can be administered as any derivative that upon administration to the recipient, is capable of providing directly or indirectly, the parent compound, or that exhibits activity itself. Nonlimiting examples are the pharmaceutically acceptable salts (alternatively referred to as xe2x80x9cphysiologically acceptable saltsxe2x80x9d), and the 5xe2x80x2 and N4 acylated or alkylated derivatives of the active compound (alternatively referred to as xe2x80x9cphysiologically active derivativesxe2x80x9d). In one embodiment, the acyl group is a carboxylic acid ester in which the non-carbonyl moiety of the ester group is selected from straight, branched, or cyclic alkyl, alkoxyalkyl including methoxymethyl, aralkyl including benzyl, aryloxyalkyl such as phenoxymethyl, aryl including phenyl optionally substituted with halogen, C1 to C4 alkyl or C1 to C4 alkoxy, sulfonate esters such as alkyl or aralkyl sulphonyl including methanesulfonyl, the mono, di or triphosphate ester, trityl or monomethoxytrityl, substituted benzyl, trialkylsilyl (e.g. dimethyl-t-butylsilyl) or diphenylmethylsilyl. Aryl groups in the esters optimally comprise a phenyl group. The alkyl group can be straight, branched, or cyclic, and is optimally a C1 to C18 group.
Modifications of the active compound, specifically at the N4 and 5xe2x80x2-O positions, can affect the bioavailability and rate of metabolism of the active species, thus providing control over the delivery of the active species. Further, the modifications can affect the antiviral activity of the compound, in some cases increasing the activity over the parent compound. This can easily be assessed by preparing the derivative and testing its antiviral activity according to the methods described herein, or other method known to those skilled in the art.
Since the 1xe2x80x2 and 4xe2x80x2 carbons of the carbohydrate of the nucleoside (referred to below generically as the sugar moiety) of the nucleosides are chiral, their nonhydrogen substituents (the pyrimidine or purine base and the CH2OR groups, respectively) can be either cis (on the same side) or trans (on opposite sides) with respect to the sugar ring system. The four optical isomers therefore are represented by the following configurations (when orienting the sugar moiety in a horizontal plane such that the Y substituent is in the back): cis (with both groups xe2x80x9cupxe2x80x9d, which corresponds to the configuration of naturally occurring nucleosides), cis (with both groups xe2x80x9cdownxe2x80x9d, which is a nonnaturally occurring configuration), trans (with the C2xe2x80x2 substituent xe2x80x9cupxe2x80x9d and the C4xe2x80x2 substituent xe2x80x9cdownxe2x80x9d), and trans (with the C2xe2x80x2 substituent xe2x80x9cdownxe2x80x9d and the C4xe2x80x2 substituent xe2x80x9cupxe2x80x9d). The xe2x80x9cD-nucleosidesxe2x80x9d are cis nucleosides in a natural configuration and the xe2x80x9cL-nucleosidesxe2x80x9d are cis nucleosides in the nonnaturally occurring configuration.
As known to those skilled in the art of nucleoside chemistry, in some cases, one of the xcex2-cis enantiomers can be more active, or less toxic, than the other enantiomer. This can be easily determined by separating the enantiomers and testing the activity and cytotoxicity using standard assays.
II. Preparation of the Active Compounds
The nucleosides disclosed herein for the treatment of HIV and HBV infections in a host organism can be prepared according to published methods. xcex2-L-Nucleosides can be prepared from methods disclosed in, or standard modifications of methods disclosed in, for example, the following publications: Jeong, et al., J. of Med. Chem., 36, 182-195, 1993; European Patent Application Publication No. 0 285 884; Gxc3xa9nu-Dellac, C., G. Gosselin, A.-M. Aubertin, G. Obert, A. Kirn, and J.-L. Imbach, 3-Substituted thymine xcex1-L-nucleoside derivatives as potential antiviral agents; synthesis and biological evaluation, Antiviral Chem. Chemother. 2:83-92 (1991); Johansson, K. N. G., B. G. Lindborg, and R. Noreen, European Patent Application 352 248; Mansuri, M. M., V. Farina, J. E. Starrett, D. A. Benigni, V. Brankovan, and J. C. Martin, Preparation of the geometric isomers of DDC, DDA, D4C and D4T as potential anti-HIV agents, Bioorg. Med. Chem. Lett. 1:65-68 (1991); Fujimori, S., N. Iwanami, Y. Hashimoto, and K. Shudo, A convenient and stereoselective synthesis of 2xe2x80x2-deoxy-xcex2-L-ribonucleosides, Nucleosides and Nucleotides 11:141-349 (1992); Gxc3xa9nu-Dellac, C., G. Gosselin, A.-M. Aubertin, G. Obert, A. Kirn, and J.-L. Imbach, 3-Substituted thymine xcex1-L-nucleoside derivatives as potential antiviral agents; synthesis and biological evaluation, Antiviral Chem. Chemother. 2:83-92 (1991); Holy, A, Synthesis of 2xe2x80x2-deoxy-L-uridine, Tetrahedron Lett. 2:189-192 (1992); Holy, A., Nucleic acid components and their analogs. CLIII. Preparation of 2xe2x80x2-deoxy-L-ribonucleosides of the pyrimidine series. Collect Czech Chem Commun. 37:4072-4087 (1992); Holy, A, 2xe2x80x2-deoxy-L-uridine: Total synthesis of a uracil 2xe2x80x2-deoxynucleoside from a sugar 2-aminooxazoline through a 2,2xe2x80x2 anhydronucleoside intermediate. In: Townsend L B, Tipson R S, ed. Nucleic Acid Chem, New York: Wiley, 1992: 347-353. vol 1) (1992); Okabe, M., R.-C. Sun, S. Tan, L. Todaro, and D. L. Coffen, Synthesis of the dideoxynucleosides ddC and CNT from glutamic acid, ribonolactone, and pyrimidine bases. J Org Chem. 53:4780-4786 (1988); Robins, M. J., T. A. Khwja, and R. K. Robins. Purine nucleosides. XXIX. Synthesis of 21-deoxy-L-adenosine and 21-deoxy-L-guanosine and their alpha anomers. J Org Chem. 35:363-639 (1992); Gxc3xa9nu-Dellac, C., Gosselin G., Aubertin A-M, Obert G., Kirn A., and Imbach J-L, 3xe2x80x2-Substituted thymine xcex1-L-nucleoside derivatives as potential antiviral agents; synthesis and biological evaluation. Antiviral Chem. Chemother. 2(2):83-92 (1991); Gxc3xa9nu-Dellac, C., Gosselin G., Imbach J-L; Synthesis of new 2xe2x80x2-deoxy-3xe2x80x2-substituted-xcex1-L-threo-pentofuranonucleosides of thymine as a potential antiviral agents. Tet Lett 32(1):79-82 (1991); Gxc3xa9nu-Dellac, C., Gosselin G., Imbach J-L, Preparation of new acylated derivatives of L-arabino-furanose and 2-deoxy-1-erythro-pentofuranose as precursors for the synthesis of 1-pentofuranosyl nucleosides. 216:240-255 (1991); and Gxc3xa9nu-Dellac, C., Gosselin G., Puech F, et al. Systematic synthesis and antiviral evaluation of xcex1-L-arabinofuranosyl and 2xe2x80x2-deoxy-xcex1-L-erythro-pento-furanosyl nucleosides of the five naturally occurring nucleic acid bases. 10(b):1345-1376 (1991).
xcex2-D-Dioxolane-nucleosides can be prepared as disclosed in detail in PCT/US91/09124. The process involves the initial preparation of (2R,4R)- and (2R,4S)-4-acetoxy-2-(protected-oxymethyl)-dioxolane from 1,6-anhydromannose, a sugar that contains all of the necessary stereochemistry for the enantiomerically pure final product, including the correct diastereomeric configuration about the 1 position of the sugar (that becomes the 4xe2x80x2-position in the later formed nucleoside). The (2R,4R)- and (2R,4S)-4-acetoxy-2-(protected-oxymethyl)-dioxolane is condensed with a desired heterocyclic base in the presence of SnCl4, other Lewis acid, or trimethylsilyl triflate in an organic solvent such as dichloroethane, acetonitrile, or methylene chloride, to provide the stereochemically pure dioxolane-nucleoside.
Enzymatic methods for the separation of D and L enantiomr of cis-nucleoside are disclosed in, for example, Nucleosides and Nucleotides, 12(2), 225-236 (1993); European Patent Application Nos. 92304551.2 and 92304552.0 filed by Biochem Pharma, Inc.; and PCT Publication Nos. WO 91/11186, WO 92/14729, and WO 92/14743 filed by Emory University.
Separation of the acylated or alkylated racemic mixture of D and L enantiomers of cis-nucleosides can be accomplished by high performance liquid chromatography with selected chiral stationary phases, as disclosed, for example, in PCT Publication No. WO 92/14729.
Mono, di, and triphosphate derivatives of the active nucleosides can be prepared as described according to published methods, The monophosphate can be prepared according to the procedure of Imai et al., J. Org. Chem.,34(6), 1547-1550 (June 1969). The diphosphate can be prepared according to the procedure of Davisson et al., J. Org. Chem., 52(9), 1794-1801 (1987). The triphosphate can be prepared according to the procedure of Hoard et al., J. Am. Chem. Soc., 87(8), 1785-1788 (1965).
Other references disclosing useful methods that can be used or adapted for the preparation of the active compounds include Hutchinson, D. W. xe2x80x9cNew Approaches to the Synthesis of Antiviral Nucleosidesxe2x80x9d TIBTECH, 1990, 8, 348; Agrofoglio, L. et al. xe2x80x9cSynthesis of Carbocyclic Nucleosidesxe2x80x9d Tetrahedron, 1994, 50, 10611; Dueholm, K. L.; Pederson, E. B. Synthesis, 1994, 1; Wilson, L. J., Choi, W.-B., Spurling, T., Schinazi, R. F., Cannon, D., Painter, G. R., St.Clair, M., and Furman, P. A. The Synthesis and Anti-HIV Activity of Pyrimidine Dioxanyl Nucleoside Analogues. Bio. Med. Chem. Lett., 1993, 3, 169-174; Hoong, L. K., Strange, L. E., Liotta, D. C., Koszalka, G. W., Burns, C. L., Schinazi, R. F. Enzyme-mediated enantioselective preparation of the antiviral agent 2xe2x80x2, 3xe2x80x2-dideoxy-5-fluoro-3xe2x80x2-thiacytidine [(xe2x88x92)-FTC] and related compounds. J. Org. Chem., 1992, 57, 5563-5565; Choi, W.-B., Wilson, L. J., Yeola, S., Liotta, D. C., Schinazi, F. R. In situ complexation directs the stereochemistry of N-glycosylation in the synthesis of oxathiolanyl and dioxolanyl nucleoside analogues. J. Amer. Chem. Soc., 1991, 113, 9377-9379; Choi, W.-B., Yeola, S., Liotta, D. C., Schinazi, R. F., Painter, G. R., Davis, M., St.Clair, M., Furman, P. A. The Synthesis, Anti-HIV and Anti-HBV Activity of Pyrimidine Oxathiolane Nucleoside Analogues. Bio. Med. Chem. Lett., 1993, 3, 693-696; Wilson, J. E., Martin, J. L., Borrota-Esoda, K., Hopkins, S. E., Painter, G. R., Liotta, D. C., Furman, P. A. The 5xe2x80x2-Triphosphates of the (xe2x88x92)- and (+)-Enantiomers of Cis-5-Fluoro-1-[2-(hydroxymethyl)-1,3-Oxathioan-5-yl] Cytosine Equally Inhibit Human Immunodeficiency Virus Type-1 Reverse Transcriptase. Antimicrob. Agents Chemother., 1993, 37, 1720-1722.
The following working example provides a method for the preparation of 5-carboxamide-2xe2x80x2,3xe2x80x2-dideoxy-3xe2x80x2-thiauridine. Melting points were determined on an Electrothermal IA 8100 digital melting point apparatus and are uncorrected. 1H and 13C NMR spectra were recorded on a General Electric QE-300 (300 MHz) spectrometer; chemical shifts are reported in parts per million (d) and signals are quoted as s (singlet), d (doublet), t (triplet), or m (multiplet). UV spectrum were recorded on Shimadzu UV-2101PC spectrophotometer and FTIR spectra were measured on a Nicolet Impact 400 spectrometer. Mass spectroscopy was performed with JEOL (JMS-SX102/SX102A/E) spectrometer. Experiments were monitored using TLC analysis performed on Kodak chromatogram sheets precoated with silica gel and a fluorescent indicator. Column chromatography, employing silica gel (60-200 mesh; Fisher Scientific, Fair Lawn, N.J.) was used for the purification of products. Tetrakis-(triphenylphosphine)palladium (0) and other chemicals were purchased from Aldrich Chemical Company (Milwaukee, Wis.). Microanalyses were performed at Atlantic Microlab Inc. (Norcross, Ga.). NMR Enzymes were purchased from Amano International Enzyme Co. (Troy, Va.).